Manually actuated fluidic igniter

ABSTRACT

An igniter in which an enclosed source of compressed fluid is disposed in a housing, and is opened by a manually actuated lever. The resulting flow of fluid is directed towards an intermediate wall formed in the housing and into a cavity formed in the intermediate wall to create pressure waves of fluid which pass through the cavity and result in a temperature rise at the closed end of the cavity. An explosive is disposed in heat exchange relation with the closed end of the cavity and is adapted to be ignited by the temperature rise.

United States Patent {72] Inventor Edward L. Rakowsky Kinnelon, NJ. 21 Appl. No, 869,610 [22] Filed Oct. 27, 1969 [45] Patented Dec. 28, 1971 [73] Assignee The Singer Company New York, N.Y.

[54] MANUALLY ACTUATED FLUIDIC IGNITER 4 Claims, 1 Drawing Fig.

[52] U.S. Cl 102/70, 102/81, 89/7 [51] Int. Cl F42c 5/00 (50] Field of Search 102/70, 81, 49.7, 27; 181/.5;89/7; 124/11, 13

[56] References Cited UNITED STATES PATENTS 2,725,048 11/1955 Koogle 124/11 3,207,143 9/1965 Kline et al 124/11 3,277,825 10/1966 Maillard l02/49.7 3,302,523 2/1967 Van Langenhoven et 89/7 Primary Examiner-Samuel W. Engle A!:0rneysS. A. Giarratana and S. Michael Bender ABSTRACT: An igniter in which an enclosed source of compressed fluid is disposed in a housing, and is opened by a manually actuated lever. The resulting flow of fluid is directed towards an intermediate wall formed in the housing and into a cavity formed in the intermediate wall to create pressure waves of fluid which pass through the cavity and result in a temperature rise at the closed end of the cavity. An explosive is disposed in heat exchange relation with the closed end of the cavity and is adapted to be ignited by the temperature rise.

PATENTEnniczslen 3,330,151

Edward L. Palm/sky INVENTOR.

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MANUALLY ACTUATED FLUIDIC IGNITER BACKGROUND OFTHE INVENTION The invention herein described was made in the course of or under a contract or subcontract thereunder, with the Department of the Army.

This invention relates to a manually actuated fluidic igniter and, more particularly, to such an igniter which initiates a solid grain propellant hot gas generator.

Most solid grain igniters and gas generators employ an electrically initiated squib, or exploding bridge, to trigger an explosive pyrotechnic chain of charges to ignite the generator. However, due to a low-power consumption of the electrical initiator, false triggering can be induced by lightning, static electricity, radiofrequency interference, nuclear radiation and the like. Some proposals have been made which utilize a fluidic ignition, but these require an external fluid supply which is expensive and cumbersome, and thus prohibitive to many applications.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an igniter which is fluidically initiated, yet does not require an external fluid supply.

Toward the fulfillment of this object, the igniter of the present invention comprises a housing, an enclosed source of compressed fluid disposed in said housing, manually actuated means for opening said source of compressed fluid, an intermediate wall formed in said housing in a spaced relation to said source of compressed fluid, a cavity formed in said intermediate wall and having an open end and a closed end, means to direct said fluid from said source against said wall and into said cavity to create pressure waves of fluid which pass through the entire length of said cavity to said closed end to cause a temperature rise at said closed end, and explosive means in heat exchange relation with said closed end and adapted to be ignited by said temperature rise.

BRIEF DESCRIPTION OF THE DRAWING Reference is now made to the accompanying drawing for a better understanding of the nature and objects of the present invention. The drawing illustrates the best mode presently contemplated for carrying out the objects of the invention and is not to be construed as restrictions or limitations on its scope. The drawing is a cross-sectional view of the igniter of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring specifically to the drawing, the reference numeral refers, in general, to a housing having a chamber formed therein which receives a standard cartridge 12 containing a compressed fluid, such as CO for example. A lever I4 extends through an end wall of the housing 10 and is slidably mounted with respect thereto by means of an O-ring seal 15. The lever can be moved outwardly in a direction indicated by the arrow a by manually pulling a lanyard 16 in the same direction.

The above movement of the lever 14 causes a corresponding movement of a cam 18 engaging the cartridge 12 and pivotably mounted with respect to a protruding member extending inwardly from the end wall of the housing to cause an axial movement of the cartridge. After a small amount of movement, the end of the cartridge 12 engages a puncturing spike 20 mounted in a reduced portion of the chamber. This engagement causes a puncturing of the end of the cartridge l2 and a resultant escaping of the gas contained therein. A converging nozzle 22 is formed at the end of the chamber housing the cartridge 12, so that gas escaping from the punctured end of the cartridge 12 will flow from the nozzle into an opening 24 formed between the discharge end of the nozzle 22 and a rigid body portion 25 of the housing 10.

A tapered resonance cavity 26 is formed in the body portion 25 and terminates a slight distance from a notch formed in the body portion, which notch receives a pyrotechnic explosive 28 of any known type, such as a lead azide. A solid grain propellant 30 is disposed in an additional chamber formed in the housing 10 in communication with the above notch and may be in the form of an ammonium percholate cast in the form of a tube having a hollow portion 32. An outlet 34 is provided in the other end of the housing 10, and provides an exit for the gas generated from the propellant 30.

In operation, upon manual actuation of the lanyard 16 in the direction indicated by the arrow a," the rod 15 will move in the same direction and cause a pivoting of the cam member 18, which, in turn, urges the cartridge 12 axially until the spike 20 punctures the end of the cartridge and causes the compressed gas to enter in, and flow through, the nozzle 22 into the opening 24.

remaining portion impinges upon the front wall of the body portion 25 and exits from the housing 10 in a direction at right angles to the direction of flow into the cavity 26. After a very short time the cavity 26 fills up and the entire flow impinges off of the above wall and exits from the housing. In this manner an unstable wave will be formed at the entrance to the cavity 26, which wave oscillates back and forth and causes small pressure waves to travel the length of the cavity 26 and compress the gas trapped at the closed end thereof, thus adding energy to the gas at every cycle of oscillation. Accumulation of this energy input per cycle causes the temperature at the closed end of the cavity 26 to rise appreciably to a point whereby it ignites the explosive 28.

The resultant release of thermal energy is sufficient to ignite the solid grain propellant 30, and the presence of the hollow portion 32 in the latter aids in the distribution of the thermal energy to the propellant and facilitates the flowing of the hot gas thus generated to the outlet 34. This gas may be used for many applications, such as to ignite a rocket engine or the like.

It is noted that the flow from the nozzle 22 can be supersonic, in which case the wave created at the entrance to the cavity 26 will be a shock wave.

The igniter of the present invention thus eliminates the effect of electrical induction and other cross-coupling inputs from an adverse environment, while utilizing a relatively inexpensive self-contained source of compressed air. Further, the igniter is very rugged, and simple in design.

It is understood that variations can be made in the foregoing without departing from the inventive concept. For example, the resonance cavity 26 does not necessarily have to .be tapered but may be cylindrical or rectangular throughout its cross section. Also, the nozzle 22 can take other configurations, such as a convergent-divergent type, etc. Other variations of the specific construction and arrangement of the igniter disclosed above can be made by those skilled in the art without departing from the invention as defined in the appended claims,

lclaim:

1. An igniter comprising a housing, an enclosed source of compressed fluid disposed in said housing, means for opening said source of compressed fluid, an intermediate wall formed in said housing in a spaced relation to said source of compressed fluid, a cavity formed in said intermediate wall, said cavity having a longitudinal axis, said cavity having an open end and a closed end, said cavity having a tapered sidewall, said tapered sidewall converging toward said closed end, means to direct said fluid from said source against said wall and into said cavity to create pressure waves of fluid which pass through the entire length of said cavity to said closed end to cause a temperature rise at said closed end, said means to direct said fluid including a nozzle portion, said nozzle portion having a longitudinal passage having an outlet opening facing the open end of said cavity coaxially therewith, said means to direct said fluid having a transverse passage connected to and disposed transverse to said longitudinal passage, and explosive means in heat exchange relation with said closed end and adapted to be ignited by said temperature rise.

2. The igniter of claim 1 wherein said enclosed source of compressed fluid is in the form of a cartridge, and wherein said housing further includes a rigid portion, said rigid portion having an end face having a notch formed therein, said notch containing said explosive means, and wherein said rigid portion has an end wall portion disposed between said notch and said cavity closed end.

3. The igniter of claim 2 wherein said means for opening said source comprises a lever slidably mounted with respect to said housing, a cam operatively connected to said lever and pivotably mounted in said housing, said cam engaging one end of said cartridge and adapted to pivot in response to a pull on said rod and urge said cartridge axially in said housing, and spike means fixed with respect to said housing and adapted to puncture the other end of said cartridge upon said axial movement, and wherein said transverse passage has an inlet end and an outlet end, said transverse passage being arranged to diverge in a direction toward said outlet end.

4. The igniter of claim 3 further comprising a solid grain propellant disposed in said housing in proximity to said explosive, said propellant adapted to be ignited by the thermal energy produced by the ignition of said explosive. 

1. An igniter comprising a housing, an enclosed source of compressed fluid disposed in said housing, means for opening said source of compressed fluid, an intermediate wall formed in said housing in a spaced relation to said source of compressed fluid, a cavity formed in said intermediate wall, said cavity having a longitudinal axis, said cavity having an open end and a closed end, said cavity having a tapered sidewall, said tapered sidewall converging toward said closed end, means to direct said fluid from said source against said wall and into said cavity to create pressure waves of fluid which pass through the entire length of said cavity to said closed end to cause a temperature rise at said closed end, said means to direct said fluid including a nozzle portion, said nozzle portion having a longitudinal passage having an outlet opening facing the open end of said cavity coaxially therewith, said means to direct said fluid having a transverse passage connected to and disposed transverse to said longitudinal passage, and explosive means in heat exchange relation with said closed end and adapted to be ignited by said temperature rise.
 2. The igniter of claim 1 wherein said enclosed source of compressed fluid is in the form of a cartridge, and wherein said housing further includes a rigid portion, said rigid portion having an end face having a notch formed therein, said notch containing said explosive means, and wherein said rigid portion has an end wall portion disposed between said notch and said cavity closed end.
 3. The igniter of claim 2 wherein said means for opening said source comprises a lever slidably mounted with respect to said housing, a cam operatively connected to said lever and pivotably mounted in said housing, said cam engaging one end of said cartridge and adapted to pivot in response to a pull on said rod and urge said cartridge axially in said housing, and spike means fixed with respect to said housing and adapted to puncture the other end of said cartridge upon said axial movement, and wherein said transverse passage has an inlet end and an outlet end, said transverse passage being arranged to diverge in a direction toward said outlet end.
 4. The igniter of claim 3 further comprising a solid grain propellant disposed in said housing in proximity to said explosive, said propellant adapted to be ignited by the thermal energy produced by the ignition of said explosive. 